This invention relates to novel catalysts for hydroformylation and hydroesterification of olefins, to a method for the manufacture of these novel catalysts, and to hydroformylation and hydroesterification of olefins by use of said catalysts.
Of the catalysts suggested to date for use in hydroformylation (oxo reaction) of olefins, those of particular importance are cobalt carbonyl, rhodium carbonyl and derivatives thereof. Those substances which give rise to such compounds in the reaction system may be similarly be used. Since hydroformylation is a reaction which is carried out in a liquid phase having the catalyst uniformly dissolved therein, separation of the catalyst from the hydroformylation product calls for a special measure. Particularly when the hydroformylation is carried out by using a cobalt type ctalyst, the separation of cobalt carbonyl from the resultant product has been a very important problem from the industrial point of view. In this connection numerous patents including U.S. Pat. No. 3,636,159 and 3,652,676 have issued to date. Actually, however, the separation of cobalt carbonyl has heretofore been performed preponderantly by following the methods to be described herein below: One method comprises heating the reaction product to have cobalt carbonyl thermally decomposed and subsequently educing the cobalt in the form of metallic cobalt. The other method comprises treating the reaction product with an organic acid or inorganic acid to have cobalt carbonyl converted into an oil-soluble, water-soluble or water-insoluble cobalt salt and subsequently separating the cobalt salt by such means as distillation or extraction, depending on the behavior of said cobalt salt or educing it in a solid form. The metallic cobalt or cobalt salt separated by these methods is converted again to cobalt carbonyl in a separate stage of process and put to use as the catalyst for the next cycle of oxo reaction. Otherwise, the metallic cobalt or cobalt salt may be recycled to the reaction system in its unaltered form. In this case, the interior of the oxo reaction vessel is required to be placed under conditions which permit conversion of the metallic cobalt or cobalt salt into cobalt carbonyl. The conditions involved herein are elevated temperature and increased pressure such as, for example, 150.degree. - 200.degree. C and 200 - 300 atmospheres. Another method available for the recovery of cobalt carbonyl comprises the steps of converting cobalt carbonyl into water-soluble NaCo(CO).sub.4 by using Na.sub.2 CO.sub.3, separating the conversion product in the form of aqueous solution and having the separated aqueous solution reacted upon by sulfuric acid to produce HCO(CO).sub.4, which is recycled to serve as the catalyst in the oxo reaction system. Recently, a method for separating cobalt carbonyl by the steps of treating the reaction product with a high molecular coordinating agent for thereby converting cobalt carbonyl into an insoluble solid and subsequently separating the solid from the system has been under study. The conventional methods described above invariably call for special stages of treatment designed exclusively for the recovery of the catalyst in question. It is also known that a complex of cobalt carbonyl comprising a substituted pyridine with electronegative non-hydrocarbon group is a catalyst good for the oxo reaction (see U.S. Pat. No. 3,231,621). However, the catalyst removal in this case requires a special measure. In the case of the catalyst for hydroesterification, the method of U.S. Pat. No. 3,507,891 has been known. This method also requires use of special means for the separation and reuse of the catalyst.
A primary object of this invention is to provide novel catalysts for use in hydroformylation and hydroesterification of olefins which are active at an extraordinarily low temperature and under an extraordinarily low pressure, and which can be separated with extreme ease.
Another object of this invention is to provide a method for the manufacture of complexes which are novel catalysts for use in the hydroformylation and hydroesterification of olefins.
Still another object of this invention is to provide a method for the hydroformylation and hydroesterification of olefins by the use of said novel catalysts.